<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>let</title>
</head>
<body>
<script>
  //声明变量
  let a;
  let b,c,d;
  let e = 100;

  //1.声明变量不能重复
  let star = "aa";
  let star = "bb";

  //2.块级作用域(if,else,while,for)，全局，函数，eval
  {
    let girl = "zzz";
  }
  console.log(girl);

  //3.不存在变量提升
  console.log(song);
  let song = "ttt";

  //4.不影响作用域链
  {
    let school = "atguigu";
    function fn(){
      console.log(school);
    }
    fn();
  }
</script>
</body>
</html>